Gareth Evans: 'People develop their own ways of handling their dog … it means they are working well together.'

I'm blindfolded and frightened. Cars are roaring past as I stumble along busy Leamington Spa pavements, terrified I'll unwittingly stray into the path of a vehicle. But Spriggs, the black labrador whose brown training harness I'm desperately clinging to, soon has me at ease, calmly steering me around hidden obstacles, pedestrians, workmen and parked cars with every wag of his tail.

Spriggs is close to finishing his training with Guide Dogs for the Blind and will soon be partnered with a visually impaired person, working until he is around 10 years old to protect his owner from the many dangers people with sight problems face out of the home.

At some point Spriggs will have been tutored by Gareth Evans, a local man who has worked with the charity for close to 16 years. "It has to be a partnership when you take on a guide dog," he explains. "We can only get the dogs to a certain level and then the owners have to take over and they will get out of that partnership what they put in."

Evans grew up in nearby Warwick surrounded by puppies – his family were regular "puppy walkers" for the charity, the name given to families that look after a puppy for its first 12-14 months before handing it back for training, as well as breeders.

"We would frequently bump into owners who had our puppies as adults, so guide dogs have always been in my life and I'd always wanted to work for the charity."

He achieved that ambition when he was 19, spending five years working in the kennels before a broken wrist led him to shadow the organisation's rehab workers, who provide training and guidance to help people live independently. "What impressed me most was how you could give someone the smallest piece of advice, some of it not even related to dogs, that would make a huge difference to their lives, such as how to make the text on their television screen bigger," he remembers. "So I retrained as a rehab worker and did that for eight years."

For three years of that, Evans was contracted out to the local authority's social services teams. "It meant that I met people at the very beginning of their journey, people just coming to terms with their sight loss. It's like a bereavement and people go through a range of emotions, so it can be tough as you can't always give them what they want – which is their sight back."

Four years ago he became a mobility instructor for the charity, which means that as well as finishing off the dogs' tuition with advanced training, he helps match dogs to owners, provides support while they get to know each other and makes annual aftercare visits. "People develop their own ways of handling their dog … it's great to see that because it means they are working well together."

I am given a quick tour of the kennels at the Leamington Spa site, where more than 1,300 guide dogs are born each year. Every row of kennels has an area where the dogs are groomed and checked daily to ensure any health issues are nipped in the bud, though the dogs only spend a short time there because they are usually out training and exercising. "Guide dogs have to be in peak condition," Evans says. "We can't pair them with a member of the public if they have a problem that could be difficult to maintain or might worsen over time."

We watch as three dogs chase each other around a grassy paddock strewn with features they might encounter in real life: tyres, ropes, ramps and jumps – all of which are designed to ensure they encounter as many real world obstacles as possible in their training. "It's amazing how many things can startle an unprepared dog out of the home," Evans explains. "A car reversing, people running past, workmen."

Loneliness isn't an issue, either – the kennels are staffed from 7am until 9.30pm, and any dogs that have problems adjusting to life there are, instead, allowed to spend time in the charity's offices – which explains the occasional child safety gate or sleeping dog around the place. There is even a "chill-out" room on site, featuring a settee and toys which stressed pooches can use for a bit of doggy downtime.

Before we make an aftercare visit, I am given a range of glasses that simulate visual impairments caused by a range of eye conditions. In each case I struggle to make out the world around me and can't wait to take the spectacles off, painfully aware of just how much I have taken my eyesight for granted.

Evans takes me to meet a visually impaired woman called Bev in the town centre to see how she's getting on with her German Shepherd, Fifi. The average age of a new guide dog owner is 49, making Bev one of the younger "mums" or "dads", as Evans calls the owners. I watch as Bev walks down the high street, Fifi deftly leading her around obstacles, at one point walking right in front her, causing Bev to stop suddenly. Fifi had seen someone about to witlessly walk across Bev's path, and had helped prevent an unwelcome shock and a possible fall.

Evans thinks there are many myths about the role of guide dogs. "A lot of people think they take their owners for a walk, that the owner says 'right, off to the fish and chip shop, please' and the dog takes them there," he says. "The owners are the ones in control and who need to know where they are going. The dog is only helping them look out for roads and obstacles, it's not actually taking them anywhere – although if it learns a route it might pop into a shop if the owner visits frequently."

He talks of the occasional embarrassment suffered by owners whose guide dogs betray their love of takeaways by padding into the kebab shop even if the owner wishes to walk past.

A couple of times someone strokes Fifi in the street and I wonder if that is a help or a hindrance to Bev and other owners? "The dogs are at work when they are out and about, so stroking them can put them off," Evans admits. "It's nice that the public feels that way and is really interested to see such well-trained dogs, but it's probably best to ask the owner first. We never like to be rude about this because we're a charity and we accept public donations. We have a lot to thank people for."

The charity is responsible for around 8,000 dogs and pays for all training and veterinary bills during their working life. The figures speak for themselves: it costs £15 to feed a guide dog for about three weeks, £20 to buy a training harness and £3,500 for one-on-one training for the dog and its new owner. Thankfully, around 10,000 volunteers save the charity an estimated £28m a year by giving their time, and it receives a huge number of donations from wills – by this year, its 80th anniversary, it will have received 38,526 gifts in wills since inception.

The match of dog is an important part of Evans's job. He looks for qualities that will ensure a happy and lasting partnership. "Fifi is sensitive," he explains, "so we had to find a mum who would work well with her. Bev is exactly the type of person who can support and give plenty of praise to Fifi, so it is a great fit."

When I am blindfolded and partnered with Spriggs for my walk, I immediately realise how big a jump it is from trusting your own eyesight to trusting that a dog will guide you safely around town. For the first five minutes I am genuinely scared that my life is held in the paws of a canine I've never met, but I slowly become attuned to Spriggs's subtle movements, when he pulls me to the left or right to avoid obstacles or as he prepares to stop at a kerb. I marvel as he obeys my command to turn right at one pavement edge (after I've issued a loud command accompanied by repeated slaps to my right leg) and we spin round and continue our journey.

All the while Evans is telling me what to do, how to give the dog feedback, to pat him affectionately when he has done well, along with numerous other instructions. By the time I take the blindfold off I have genuinely bonded with Spriggs, to the extent that Evans jokes: "I'd better check your bag to see you haven't stolen him," and I get an inkling of the incredible bond that dogs and owners must share.

On the train back to London I spot one of Spriggs's black hairs on my leg and it reminds me of my childhood pet Sid – a Jack Russell terrier I still miss to this day. It then strikes me why Evans has been with Guide Dogs for the Blind for so many years: when you are a key part in forging so many beautiful relationships, partnerships that lead to vastly improved lives, why would you want to work anywhere else?